Single track vehicles—such as a motorcycle—comprise the characteristic that when negotiating curves they require an appropriate transverse tilt in the respective steering direction. A corresponding force is generated by means of the so-called “angle of tilt” of the vehicle in the direction of the curve center point and the force counteracts the centrifugal force that acts on the vehicle and that increases as the velocity increases. Without tilting in this manner, the vehicle would, so to speak, tip over when negotiating a curve.
A similar stability problem arises in the case of multi-track vehicles, in particular two-track vehicles on at least one axle, which have a small track width. In this case, the opposing moment that arises from the vehicle weight and track width is no longer sufficient above an individual curve velocity. As a result, the wheel of the axle that is on the inside of the curve can lose its contact with the ground during a steering maneuver. In this state, when the velocity is above a specific value, the vehicle is in danger of tilting over opposite to the curve direction and, consequently, tipping out of the curve.
Therefore, in addition to lowering the center of gravity of the vehicle, vehicles of this type have been equipped with tilting technology, as a result of which the bodies of the vehicles can be tilted into the curves in a similar manner to the body of a motorcycle. The stabilizing process that is possible in this manner is similar to that which can be performed by single-track vehicles—for example, by means of the person steering the vehicle and/or by way of a suitable auxiliary means. It has been established in the case of tilting vehicles of this type that comprise at least one multi-track vehicle axle, that when the tilting vehicles are in their upright position they are generally in an unstable state of equilibrium.
In this case, it is the body that tilts and, accordingly, tips sideward with respect to the running gear without corresponding measures. In so doing, even the smallest stimulus is sufficient in order to tip the body of vehicles of this type out of its upright position or even to cause the entire vehicle to tip over. The magnitude of tilting moment that is to be counteracted increases due to the increasing length of the moment arm of the center of gravity as the tilt of the body increases.
It is possible to differentiate between a fully passive or active and occasionally semi-active tilting technology. The fully passive tilting vehicles represent the simplest implementation of this technology. In the case of the technology, the vehicle body is tilted in order to initiate the negotiation of curves and in order to stabilize the vehicle body, as in the case of a motorcycle, only by means of a steering movement in combination with a corresponding weight shift of the person steering the vehicle. Systems of this type are not easy to drive for this reason. The greater weight of a multi-track vehicle means that tilting running gears that are constructed in such a simple manner do not function or at least do not function in a satisfactory manner.
Fully active tilting mechanisms offer maximum support, since the angle of tilt of the vehicle is monitored at each point in time and is automatically corrected as required. This embodiment requires a suitable actuator that actively implements the correcting procedures and in this manner transmits them to the wheel suspension. It is necessary for this purpose that the actuator is permanently providing a force and the actuator must be sufficiently powerful for this purpose. In addition to the associated increase in weight, the high costs for a tilting technology of this type are also to be mentioned. As a result, vehicles that are equipped in this manner also provide less pleasure when driving the vehicle, which is a result of the unnatural driving sensation. Additional factors are the occasionally quite costly body and the high costs that arise for actuators that are to be embodied in a correspondingly robust manner and are accordingly heavy. Last but not least, bodies of this type require an appropriate amount of installation space since their dimensions could otherwise not be accommodated.
It is apparent from this that tilting running gears require suitable stabilizing means in order to be able to move vehicles of this type safely and comfortably and with a pleasant driving sensation. In view of the illustrated disadvantages of fully passive and active tilting systems, the technology required for this purpose still continues to offer room for improvements.
In particular, there is yet to be a stabilizing arrangement and a tilting running gear for a non-rail-borne vehicle that renders possible a cost-effective body and an easier handling of the vehicle so equipped.